Phase transitions in optimal strategies for betting

Kelly's criterion is a betting strategy that maximizes the long term growth rate, but which is known to be risky. Here, we find optimal betting strategies that gives the highest capital growth rate while keeping a certain low value of risky fluctuations. We then analyze the trade-off between the average and the fluctuations of the growth rate, in models of horse races, first for two horses then for an arbitrary number of horses, and for uncorrelated or correlated races. We find an analog of a phase transition with a coexistence between two optimal strategies, where one has risk and the other one does not. The above trade-off is also embodied in a general bound on the average growth rate, similar to thermodynamic uncertainty relations. We also prove mathematically the absence of other phase transitions between Kelly's point and the risk free strategy.Comment: 23 pages, 5 figure

Understanding exploratory use of ERP systems

One way for organizations to move from superficial to more comprehensive usage is to get users to go beyond the basic capabilities of the system and to uncover new ways of using it, either on their own or with the help of others, i.e., through exploratory use. This study focuses on ERP systems as an example of complex IT. Building on the Theory of Planned Behavior (TPB), sets of salient behavioral, normative, and control beliefs are identified as determinants of the intention to explore

Closed-loop control strategy with improved current for a flashing ratchet

We show how to switch on and off the ratchet potential of a collective Brownian motor, depending only on the position of the particles, in order to attain a current higher than or at least equal to that induced by any periodic flashing. Maximization of instant velocity turns out to be the optimal protocol for one particle but is nevertheless defeated by a periodic switching when a sufficiently large ensemble of particles is considered. The protocol presented in this article, although not the optimal one, yields approximately the same current as the optimal protocol for one particle and as the optimal periodic switching for an infinite number of them.Comment: 4 pages, 4 figure

Subcutaneous Fat Necrosis Following Induced Hypothermia

A necrose gorda do tecido celular subcutâneo do recém-nascido está associada a asfixia neonatal, aspiração de mecónio, convulsões ou hipotermia. A hipercalcemia é a complicação mais frequente, podendo em alguns casos ser grave e exigir terapêutica específica. Relata-se o caso de um recém-nascido de cesariana emergente por sofrimento fetal, tendo sido submetido a protocolo de hipotermia induzida. Foi diagnosticado com necrose gorda do recém-nascido ao 11º dia de internamento. No 23º dia identificou-se hipercalcemia, tendo iniciado terapêutica com pamidronato, com consequente diminuição gradual da calcemia. Sublinha-se a necessidade da identificação rápida de necrose gorda, possibilitando antecipar a hipercalcemia e iniciar terapêutica precoce

Natural to anthropogenic forcing in the Holocene evolution of three coastal lagoons (Caldas da Rainha valley, western Portugal)

In the coast of Central Portugal three lagoons were created by the Holocene flooding of diapiric-related depressions but experienced afterwards a significant sediment accumulation. Fast environmental and morphological changes after the Middle Holocene were clearly forced by anthropogenic activities since the Middle Ages and show a strong feedback on the human communities. Erosion in the studied watersheds depends on climatic and anthropic changes; especially, demographic rises increase agriculture and deforestation in the watersheds, and sedimentation in the lagoons. The region was successively occupied by ethnic groups since the Neolithic (including Romans, Sueves, Visigoths and Muslims), but the main changes were largely due to anthropic forcing following the Christian Reconquest by the Kingdom of Portugal. In fact, during the Middle Ages and Renaissance the area had intense nautical, fishing and agricultural activities, even if reduced during the 14th century crisis. Later, due to severe sediment accumulation and shoaling, sailing was drastically reduced and most of the area drowned in the maximum transgression was claimed to farming. It is also noteworthy that the social evolution and sediment entrainment in the watersheds appear to be in tune with climatic trends deduced after regional and global data. In synthesis, we conclude that the human activities during the last millennium greatly accelerated the natural silting trend of the lagoons.http://www.sciencedirect.com/science/article/B6VGS-4JG5FFW-3/1/11f72540510a832159527f6b160a4c6

A CMOS signal to noise measurement circuit for infrared sectored receivers

This paper describes a circuit able to measure Signal to Noise ratios developed for Infrared applications. The Signal to Noise ratio is of major importance in IR Sectored Receivers because it provides the basis of selection or combining of signals coming from different optical sectors. This circuit estimates the ratio of the average optical signal sensed in the photo-detector and the average noise power present in the same photo-detector, with a 50dB output dynamic range.Este artigo descreve um circuito capaz de medir a Relação Sinal Ruído em sistemas de comunicação por Infravermelhos. A relação Sinal Ruído desempenha um papel fundamental em Receptores Sectorizados por IR, pois é necessária para métodos de selecção ou combinação dos sinais vindos dos diferentes sectores ópticos. O circuito aqui descrito é capaz de estimar a razão entre a potência média do sinal adquirido pelo fotodetector e a potência de ruído presente no mesmo, apresentando uma gama dinâmica de 50dB